1. Field of the Invention
The present invention relates generally to internal combustion engines and more particularly to a system for heating the intake fuel mixture of the engine by utilizing heat from the exhaust gases for this purpose. More specifically, the invention relates to a heating system which is adapted to enhance the atomization of the fuel or mixture charge in the intake manifold during low-temperature engine conditions.
2. Description of the Prior Art
It has been known in the past to provide a heating system for heating the intake fuel mixture or charge of an internal combustion engine for the general purpose of enhancing atomization of fuel flowing in the intake manifold during low-temperature engine operating conditions.
Such systems have operated to utilize the heat from the exhaust gases emitted from the engine. In this regard, continued heating of the intake manifold after engine warm up operation will cause a temperature rise in the flow chamber of the engine carburetor. In order to overcome this disadvantage or shortcoming in such systems, there is provided a heat control valve for controlling the flow rate of the exhaust gases in response to the temperature of the engine.
Detection of the engine temperature is normally achieved by utilization of a spiral bimetallic member. Normally, in a spiral bimetallic member of this type, one end of the bimetallic member is secured to a shaft of the heating control valve and the other end of the bimetallic member is secured at a given position on the exhaust pipe. As a result of this, other problems may arise in that a limitation is imposed on the extent of the reversible deformation of the spiral bimetallic member. As a result, in a case where the ambient temperature is excessively high, high stresses are likely to be imposed on the spiral bimetallic member resulting in an irreversible or permanent deformation of the member. This will occur because the spiral bimetallic member is compressed in a specific direction to a contour which causes the member to go out of roundness. This in turn will hamper the normal or proper functioning of the heating control valve. Additionally, the time duration over which the heating control valve is shifted from one valve position to another should be shortened or minimized and therefore a balance weight is secured to the shaft of the heat control valve. It follows from this that in order to prevent irreversible or permanent deformation of the spiral bimetallic member, particularly in a case where the member is of an open ended configuration as opposed to a closed end configuration, there must occur repeated cycles of abutement of the counter-weight or balance-weight on the stopper due to vibrations of the vehicle. This creates an undesirable noise and gives rise to further disadvantage.